Respiratory insufficiency affects millions of people. For patient's suffering from this condition, the lungs are unable to inspire sufficient oxygen or expel sufficient carbon dioxide to meet the needs of the cells of the patient's body. For example, Chronic Obstructive Pulmonary Disease (“COPD”) affects approximately thirteen million Americans and ten million Europeans. COPD is a disease involving some damage to the lungs. The airways and the alveoli of the lungs can lose their elastic quality. Walls between alveoli can become destroyed or they can become inflamed. The airways of the lungs may also produce more mucus than usual, which can restrict airflow. This damage will typically manifest itself in some difficulty with breathing such as dyspnea. COPD patients typically experience coughing, with an expulsion of mucus, shortness of breath, wheezing and a feeling of tightness in the chest. Emphysema and chronic obstructive bronchitis may each be considered to be a form of COPD. Chronic obstructive bronchitis may be characterized by an inflammatory response in the larger airways of the lungs. Emphysema may be characterized by destruction of tissue of the lungs from an inflammatory response.
Cigarette smoking is considered a leading cause of COPD. Most people with COPD have some history of smoking. Extensive exposure to lung irritants, such as air pollution or chemical fumes, may also contribute to COPD.
COPD may develop slowly, with the symptoms worsening over time. COPD is a significant cause of disability. COPD can make it difficult to perform physical activities such as walking or exercise. Initially, the symptoms may be most evident during vigorous activities. However, as the disease progresses, symptoms may become more evident during milder activities and even while at rest. COPD may even lead to death. It is presently the fourth leading cause of death in the United States.
There is no presently known cure for COPD. There is no treatment for restoring the airways and alveoli of the lungs of a COPD patient to their pre-disease condition. However, treatments and lifestyle changes can help a COPD patient to feel more comfortable, continue to be active and impede the progression of the disease.
There are devices that may be useful in diagnosing a patient's COPD. For example, COPD may be diagnosed with spirometry. This typically involves measuring lung function by the measurement of the volume and/or speed (flow) of air that can be inhaled and exhaled. X-rays may show a hyperinflation of the lungs and can help to exclude other lung diseases. A pulmonary function test that includes lung volume and gas transfer can show hyperinflation. This can permit a differentiation between COPD with emphysema or COPD without emphysema. A computed tomography scan of the chest at a high resolution may show a distribution of emphysema in the lungs and can help to exclude other lung diseases.
Oximetery can also assist with the analysis by showing low oxygen levels or hypoxemia and/or high carbon dioxide levels or respiratory acidosis. A blood sample can also show a high blood count that may be a reaction to long-term hypoxemia (i.e., a reactive polythycaemia).
It will be appreciated that there is a need in the art for improved techniques and devices for addressing the conditions of patients suffering from respiratory insufficiency or COPD.